Boron is often listed as a rare element abroad, but there are abundant borax minerals in China. Therefore, boron is not a rare element, but a high-yield element. Borax is also used as a solid lubricant for metal wire drawing in industry.
In the welding and maintenance of refrigeration equipment such as refrigerators, freezers and air conditioners, it is usually used as (inert) flux to purify metal surfaces. Removing the oxide on the metal surface; Add a certain proportion of sodium chloride to borax. Sodium fluoride, potassium chloride and other compounds can be used as active fluxes to weld copper pipes and steel pipes, steel pipes and steel pipes in refrigeration equipment.
Extended data
The molecular weight of borax is 38 1.37, and it is colorless translucent crystal or white crystal powder with monoclinic crystal. Odorless, salty, soluble in water and glycerol, insoluble in ethanol and acid, and weakly alkaline in aqueous solution. Its density is 1.73g/cm3, and it is weathered in dry air.
When the temperature is higher than 56℃, the pentahydrate precipitates from the solution. When the temperature is lower than 56℃, decahydrate precipitates; Heating to 350-400 DEG C to completely lose water and become anhydrous salt; Heat to 878℃ and melt into glass. Melted borax can dissolve many metal oxides and generate metaboric acid double salt with characteristic color. This property of borax is called "borax bead test". ?
Borax mainly exists in borate minerals and is commonly found in dry boron-containing salt lakes. China is rich in borax mineral resources, Tibet has a large number of natural borax, the northeast is rich in boron and magnesium minerals, and Yunnan, Xinjiang, Sichuan, Shaanxi, Gansu and other places also produce it.